Change docker module to use for_each

Copy pasted notes previously written in docker module.

TODO: This should be a resource per app (and per server for pulling) and have each app have its own resource Updating all apps based on adding/removing an app is not gentle

TODO: Causes issues when pulling from a docker registry hosting our apps images but with bad login info (invalidated deploy tokens etc.) and our kubernetes executor attempts to use an image from the same registry. It attempts to use the invalid login regardless if the image is public or not. Requires logging out from registry for kube executor to pull public image.

Roadmap is moving everything to kubernetes currently but I'd still like to support single app deployment using docker-compose up -d (with swarm support configurable)
Most apps should be on kubernetes next update

No more git cloning repo to deploy to the server
curl -O docker-compose.yml
(populate env_file if applicable)
docker-compose pull [service(s)]
docker-compose up [service] -d

TODO: Use for_each to use keys instead of indexes